Beam centering apparatus



Jan. 26, 1960 P. HELLER 2,922,909

BEAM CENTERING APPARATUS Filed April 26, 1956 Fig.2.

WITNESSES Poul Heller BY gZ- ATTORN EY BEAM CENTERING APPARATUS Paul Heller, Richmond Hill, N.Y., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 26,1956, SerialNo. 580,861 I 7 Claims. (Cl. 313.-76)

The present invention relates to apparatus for centering the electron beam on the screen of a cathode ray tube and, more particularly, to beam centering apparatus for centering of the raster onthe screen of a cathode ray tube of a television receiver.

In a cathode ray tube especially of the type used for television purposes it has been found very desirable to provide some means for centering or adjusting the undeflected position of the electron beam relative to the screen of the cathode ray tube in order that the images may be reproduced correctly centered on the screen area. One arrangement that is suitable for accomplishing beam centering comprises two annular. magnets, each permanently magnetized across its diameter. The two magnets are disposed side-by-side and are mounted for i11 dependent rotation about the neck of the cathode .ray tube. By rotating either or both of .the magnets, the strength and direction of the resultant magnetic field. along the axis of the tube neck may be changed in accordance with the relative positions of the magnets.

In my copending US. application, SerialNo. 531,720, filed August 31, 1955, and entitled Retaining Device, there is described and claimed a device which serves to retain electron beam controlling apparatus of a cathode ray tube, such as a deflection yoke, at a predetermined location along the neck of the tube. This device may also serve as a mounting for annular permanent magnets used for electron beam centering. According to that application, the annular magnets are mounted adjacent to the base portion ofthe retaining device and are rotatable about the axis of the cathode ray tube neck. The annular magnets are held against the base portion of the retaining device by the utilization of a pair of tabs that are integral with the base portion. The tabs are rolled over after the magnets are suitably positioned. Also, according to that application, springs can be' used in place of the tabs to hold the beam centering magnets adjacent the base portion of the device. V I

It is an object of the present invention to. provide an improved annular permanent magnet means for aifording beam centering in a cathode raytube. I

It is another object to provide an annular permanent magnet beam centering means whichis simpler in construction than those of the prior art.

It is still another object to provide an annular permanent magnet beam centering means which does not utilize an external or non-integral magnet holding device.

United States Patent 2,922,909 Patented Jan. 26, 1960 .neck portion to an appropriate position, usually right up against the flare portion of the tube.

A retaining device indicated by the reference numeral 18 is comprised of a base portion 20 and integral flange there will exist no relative movement between the two.

The flange portion 24 is segmented and a plurality of segments 28 extend longitudinally and outwardly from'the base portion 20. The ble material and are their free ends. from each other neck 12 so that when the retaining device on the cathode ray tube, the segments 28 will closely engage the neck. The retaining device 18 will substantially prevent the yoke 16 from rotating about the neck- 12 and it will also retain the yoke 16 location along the neck of the tube. that the device 18 be somewhat flexible in order that the segments 28 will be expanded laterally and outwardly from the axis of the neck 12 so that the segments will closely engage the neck! The segments 28 are also chamsegments 28 are made of a flexifered at both ends as shown at 30 in order to allow theyoke '16 to slip on and off the neck 12 of the cathode ray tube 10 witha minimum of interference with the base structure or socket (not shown) of the cathoderay tube 10. The longitudinally extending segments 28 have a suflicient length so that when the yoke 16 is properly positioned on the neck 12 of the tube, a clamping or mounting ring 32 may be placed over the seg ments and tightened by means of screw 34 so as to se-' curely lock the retaining device 18 and the yoke 16 to the neck 12 of the cathode ray tube. The segments 28 are'wedge-shaped so that when the retaining device 18 is placed upon the neck portion 12, their outer surfaces will be parallel to the longitudinal axis of the cathode ray tube. and there will be a minimum tendency for the clamping ring 32 to slip off the segments.

The retaining device 18 is shown as a rear or back cover for the deflection yoke 16. The device 18 is preferably made of some heat resistant material such as heat resistant cellulose acetate, sothat it will not distort excessively due to prolonged contact of the segments 28 Figure 1 is aside elevational view of a beam. centerwith the. neck 12 of the cathode ray tube 10. The device 18 is also. preferably made with the segments 28 "molded because of the facility with which the plastic material described may be shaped by that method; The base por tion 20 of the device 18 is molded with a plurality of circular ridges 35 which add structural strength-to the base portion. It will be understood that any other mode of shaping which' seems'appropriate may also be employed.

Two annular permanent. magnets 36 and 38 are used for centering of the electron beam of the tube 10. Two of the tapered segments 28 of the retaining device 18 are molded with tabs 44 and 46 on their outer surfaces. The spread dimension of the tabs 44 and 46 is made largerthan the. inner diameter of the magnets 36' and 33 so' that when the magnets are pushed over the tabs 44 and 46 they become locked in place and cannot be removed from the retaining device 18 without forcibly compressing both of the tabs.

The base portion 20 of the retaining device 18 is provided with a pair of diametrically opposed bosses 48 and 50 which are molded at positions relative to the tabs 44 and 46. The bosses 48 and 50 serve to back up the mounted magnets 36 and 38. The height of the bosses 48 and 50 determines the amount of spring bow that is made to taper inwardly towards The segments 28 are laterally spaced a distance less than the diameter of the 18 is placed' at the appropriate It is most desirable the 'necesisarvamount of ,friction'on the magnets to lock;

them in position during shipping and normal vibration,

with a cathode ray tube hrrving a neck portion, said EA annulus of non-magnetic anti-rotational sheet 'ma- I terial (not shown) may be positioned between the two magnets -36 and 3 8; These'magnets are mounted up againstthe bosses 48 andS'Oadjacent the base portion of the retaining device 18 and are independently rotatableabout the axis of the neck 12 of the cathode ray tube. vThe magnets 36 and 38 are provided with ears 36A and 38A which extend beyond the periphery of the non-magnetic sheet material and facilitates turning ofthemagnets'. r {Although the invention has been described'with reference to a specific embodiment,- it will be obvious to those skilledin the art that it is not so limited but is.

susceptible to-various changes and modifications without departing from the spirit and scope thereof.

*1 claim as my invention: 7 N 1 j V l '1. Beam centering apparatus for use in conjunction with a cathode ray tube having a neck portion, said beam centering apparatus comprising: a base portion having a central aperture through which the neck portion is adapted tqjpass and having a boss projecting from one side thereof, an integral flexible flange portion extending longitudinally from said oneside of said base portion, said flange portion having at least one longitudinally extending slot therein, a pair of annular permanent magnets mounted coaxially side-by-side and surrounding said flange portion, and at least two tabs provided on the outer surface of 4. Beam centering apparatus for use in conjunction beam centering apparatus comprising: a base portion having a central aperture through which the neck portion is adapted to pass and haying a boss projecting from one side thereof, an integral flexible flange portion also extending longitudinally from one side of said base portion, said flange portion having at least two segments tapered toward their free ends, a pair of annular permanent magnets mounted coaxially side-by-side and surrounding said flange portion, and at least twotabs provided on the outer surface of said segments 'for holding i said magnets against said boss and bowed-in towards said one side of saidvbase portion when :said segments are laterally expanded to closely engage said neck portion of the tube. j V

5. Beam centering apparatus. for use in conjunction with a cathode ray tube having a neck portion, said beam centering apparatus;comprising: a base portion having a central aperture through which the neck portion is adapted to pass and having'a pair of-diametrically opposed bosses projecting longitudinally, from one side thereof, an

. integral flexible flange portion also extending longitudinally from said one sidetof said base portion, said flange portion having four segments tapered towards their free ends, a pair of annular permanent magnets mounted coaxially side-by-sideand surrounding said flange portion,: and a pair of tabs provided on diametrically opsaid flange portion foriurging said magnets axially towards v saidboss when said flange portion is laterally expanded so as to-closely engage said neck portionvofthe tube.

, 2-. Beam centering apparatus for use in conjunction with a c atho de ray tube havinga neck portion, saidbeam centering apparatus comprising: a' base portion having a central' aperturethrough which the neck portion is adapted to pass and having at least two bosses projecting fromione, side thereof, an integraltflexible flange portion extending longitudinally from said one side of said base portion, said flange portion having at least one longitudi nally extending slot therein, a pairof annular permanent magnets mounted coaxially side-by-side and surrounding saidflange portion, and at least two tabs provided on the outer surface of said flange portion for urging said 'magnetsaxiallytowards said bosses when said flange'portion islaterally expandediso as to closely engage said neck portion of the tube.

--;3.;Beam centering apparatus for use in "conjunction posed outer surfaces of two of said segments for urging said magnets axially towards said bosses when said segments are laterally expanded to closely engage said neck portion of the tube.

6. Beam centering apparatus for use in conjunction with a cathode raytube having a neck portion, said beam centering apparatus comprising: a base portion having a central aperture through whichthe neck portion is adapted to pass, a flange portion extendinglongitudinally from one side of said base portion, said flange portion having at least one longitudinally extending slot therein, a pair of annular permanent magnets mounted coaxially side-byside: and surrounding said flange portion, and at least two tabs provided on the outers'urfac'e of said flange portion for-retaining said magnets on said flange portion adjacent to said 'basefportion.

"7'. Beam centering apparatus for use in conjunction with a cathode ray tube ha'vinga neck portion, said beam centering" apparatus'comprising: a base portion having 1 a central aperture through which the neck portion is withacathode ray tube having a neck portion, said beam 7 centering apparatus comprising: a base portion having a central aperture through which theneck portion is adapted to pass and having a'pair of diametrically opposed bosses projecting longitudinally from one side thereof, anintegral flexible flange portionalso extending longitudinally from saidone side of said base portion, said flange por 8 tion having at least two segments tapered towards their, free ends, apair of annular permanent magnets mounted coaxially side-by-side and surrounding said flange portion, and a pair of tabs provided on diametrically opposed outer surfaces of said segments for urging said magnets axially towards said bosses when said segments are laterally expanded to closely engage the neck of the tube.-

adapted to pass, a flange portion extendinglongitudinally from one side of said base "portion,said flange "portion having-at least two segments tapered towards their use endsf a pair oi annular 3 permanent v magnets mounted coaxially iside-by-side and surrounding said flange portion,

and a pair of tabsprovided on'diametrically opposed outer surfaces of said segments fon'urging'smdmagnets axially 

